The stupidest mistake

I cancelled my "emergency" credit card. you know, the one that actually has credit available on it. The one you can go to if you need a car rental or have to travel somewhere or your car dies? I have no idea what to do. My credit is crap right now and it nots my fault. I DO pay my bills. Paying online has been a nightmare not a help. I think that they are paid only the credit companies keep screwing me somehow. Changing the due date from month to month....Walmart really screwed me up. I thought I had them all set on autopay. I was set to pay them $30 a month for 5 months. Noooo, they take $30 and divide it over 5 months so they only got paid $6. Does that make any since? Or Best Buy....ever since I've had my car it was due on the 10th. Suddenly they start calling me telling me the payment is late, they changed it to the 1st! Ok so I don't open the statements...but I'm not making any charges and I pay the bills online. I am so completely fucked. I ws going to pay for school with that card. I hate to say it but I am going to have to borrow from my kids college money and pay off the cards I do have and get out of this hole. Is anyone else out there in this situation?? I was supposed to send my autistic son to camp this summer using that card. I don't know what to do. I need help badly. I feel like dying right now. Crawling in a hole and dying. Really, I don't have any reason to live because I can't face my kids. I can't pay for anything for them.